Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 12 December 2003:
Vol. 302. no. 5652, pp. 1902 - 1903
DOI: 10.1126/science.1091466
Prev | Table of Contents | Next

Perspectives

ASTRONOMY:
The Hunt for Dark Matter in Galaxies

Ken C. Freeman

Most galaxies are enveloped in huge dark halos that contain 10 to 20 times as much mass as the luminous stars and cold gas in the galaxies. Simulations of structure formation in the universe are not entirely consistent with the properties of dark halos inferred from observation. In his Perspective, Freeman discusses recent results about dark matter obtained by measuring the "gravitational lensing" of distant objects by intervening galaxies. Lensing surveys indicate that dark halos contribute about 11% of the mass of the universe, compared with about 0.4% in stars and cold gas. Intergalactic dark matter and gas probably make up another 16%, and the remaining 73% is in the form of a poorly understood "dark energy."

The author is at the Mount Stromlo Observatory, Australia National University, Weston Creek, ACT 2611, Australia. E-mail: kcf{at}mso.anu.edu.au

Read the Full Text

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)